HP / SP
Max HP grows with level (by a class factor) and is multiplied by (1 + VIT/100); SP likewise from level and INT. So VIT and INT give a percentage gain, not a flat one. Transcendent classes get +25%, baby classes −30%.
What HP and SP are
HP (Health Points) is your health, your pool of life. When HP drops to zero, your character dies. SP (Spell Points) is your mana, the pool of "fuel" for skills: almost every attack-skill, buff or heal costs a certain amount of SP, and when SP runs out you can no longer cast anything until it regenerates. Think of HP as the thickness of your skin, and SP as the fuel in the tank for everything "magical" and "active" that you can do.
The HP formula
The most important thing to understand from the very start: in pre-renewal, maximum HP and SP are NOT simply "so much per level". The formula is non-linear. First the game computes a helper sum called sigma, which accumulates with every level: sigma(lvl) = the sum over all levels from 2 to your current level of floor((HPFactor × level + 50) / 100). Then MaxHP = floor((35 + floor(lvl × HPMul / 100) + sigma) × (1 + VIT / 100)). So the HP base itself keeps growing, and the higher your level, the bigger the HP gain from each new level.
The SP formula
SP is computed more simply and more linearly: MaxSP = floor((10 + floor(lvl × SPFactor / 100)) × (1 + INT / 100)). There is no accumulating sigma here, so SP grows steadily with level, while INT multiplies the result by a percentage.
VIT and INT are a percentage
And here is the key thing about stats: VIT and INT give NOT a flat bonus but a PERCENTAGE. Look at the formulas — VIT sits inside the multiplier (1 + VIT / 100), and INT inside (1 + INT / 100). This means 80 VIT increases your MaxHP by 80% of the base, not "by so many units". That is why the same VIT gives MORE HP at a high level (because the base it multiplies is already large) and less at a low level. This is exactly why tanks pump VIT — a percentage of a large base at level 99 turns into thousands of HP.
Classes and trans
Why HPFactor, HPMul and SPFactor are DIFFERENT for each class — because that is how the game defines a "role". For Knight, HPFactor/HPMul/SPFactor = 150/500/300: lots of HP, little SP. For Wizard = 55/500/900: very little HP (HPFactor 55 versus 150 for the knight), but a large SPFactor so the mage has enough mana for powerful spells. And transcendent classes (Lord Knight, High Wizard and so on) get an extra +25% to both HP and SP on top of everything — a reward for rebirthing, which is why a trans character is always tougher and more "mana-rich" than its non-trans counterpart.
sigma = Σ_{j=2..lvl} floor( (HPFactor × j + 50) / 100 )- HPFactor
- class HPFactor (engine sigma coef.)
MaxHP = floor( (35 + floor(lvl × HPMul/100) + sigma) × (1 + VIT/100) )- lvl
- character base level
- HPMul
- class HPMultiplicator (linear coef.)
- VIT
- character VIT stat
MaxSP = floor( (10 + floor(lvl × SPFactor/100)) × (1 + INT/100) )- SPFactor
- class SPFactor
- INT
- character INT stat
| Max HP (Knight) | (35 + ⌊99·500/100⌋ + sigma[150]) × (1 + 80/100) | 14,360 |
| Max SP (Wizard) | (10 + ⌊99·300/100⌋) × (1 + 99/100) | 610 |
Take a Knight (HPFactor 150, HPMul 500) at level 99. First the base with no VIT: sigma comes out to 7448, then (35 + floor(99 × 500 / 100) + 7448) = 35 + 495 + 7448 = 7978. That is the HP at VIT 0 — exactly 7978. Now add VIT 80: 7978 × (1 + 80 / 100) = 7978 × 1.80 = 14 360 HP. See? The same character with 80 VIT gained +6382 HP — that is the "percentage of a large base".
The same Knight, VIT 80. At level 99 the difference between VIT 0 and VIT 80 was +6382 HP. But at level 20 those same eighty VIT add only +362 HP. Why? Because at level 20 the HP base is still tiny, and 80% of it is peanuts, while at level 99 the base is 7978 and 80% of it is a huge 6382. Hence the rule: VIT "unfolds" with level, so an early tank looks frail but becomes a monster at the cap.
Wizard at level 99 with INT 99: MaxSP = floor((10 + floor(99 × 900 / 100)) × (1 + 99 / 100)) = floor((10 + 891) × 1.99) = floor(901 × 1.99) = 1792 SP. A huge mana tank. But its HP at VIT 0 is only 3254 versus 7978 for the knight: HPFactor 55 versus 150 makes the mage "paper". Now trans: a High Wizard with the same INT 99 gets +25% SP → 1792 × 1.25 = 2240 SP. And a Lord Knight (the knight trans) with VIT 80 gets 14 360 × 1.25 = 17 950 HP instead of 14 360. That is why trans is always tougher.
- HP grows NON-LINEARLY: thanks to the accumulating sigma, each new level adds more HP at high levels than at low ones. Do not be scared by a "frail" character at the start — HP skyrockets at the cap.
- VIT and INT are a PERCENTAGE, not a flat bonus: (1 + VIT / 100) for HP, (1 + INT / 100) for SP. 100 VIT = doubling the HP base.
- Because it is a percentage, the same VIT/INT gives more HP/SP the higher your level — investing in stats "gets more valuable" (in a good way) as you level up.
- SP grows linearly with level (no sigma), so the mana pool is predictable: the main multipliers are INT and the class (SPFactor).
- Transcendent classes (Lord Knight, High Wizard, Sniper, Assassin Cross and so on) have +25% to both MaxHP and MaxSP on top of the whole formula — a pure bonus for rebirthing.
- HPFactor / HPMul / SPFactor are specific to EACH class. Knight 150/500/300 (tank), Wizard 55/500/900 (a glass cannon with a big mana pool). Do not compare a mage’s and a knight’s HP head-on — their coefficients differ.
- Thinking VIT adds a fixed amount of HP. No — it is a percentage of the base, so at level 1 it is almost useless, while at 99 it gives thousands of HP.
- Pumping VIT on a mage or INT on a purely physical tank "because more HP/SP". The multiplier works, but a small base (the mage’s low HPFactor) makes the HP gain tiny — a mage is better off investing in INT and surviving by range rather than by bulk.
- Wondering why a low-level character is so "paper". This is normal: the non-linear formula and percentage stats have not unfolded yet — HP will jump at high levels.
- Comparing the MaxHP of different classes as if the formula were the same for everyone. Each class has its own HPFactor/HPMul/SPFactor — a Wizard and a Knight at the same level with the same VIT will have completely different HP.
- Forgetting the +25% on trans classes. When planning a build, do not compare a High Wizard with a regular Wizard one-to-one — trans always has an HP and SP pool a quarter larger.
- Assuming SP will "just be enough". If your class has a low SPFactor (like Knight, 300) and you do not pump INT, mana will only last a few skills — plan for that in advance.
Formulas verified against the uAthena engine (pre-renewal, Episode 11.2).